MR screening of athletes could prevent injuries

The use of MR imaging to screen adolescent baseball and college basketball players may avert injuries that could take them out of the game, according to a pair of research papers presented Thursday.

A study at Duke University found that MR could be used to identify bone marrow edema in the metatarsals of basketball players. When bone marrow edema is found, prosthetic devices can be used to stop further injury and prevent stress fractures that could force a player to sit out the short and intense college basketball season, said author Dr. Nancy Major.

Another study at New York University found that humeral cortical thickness tended to be greater in the throwing arms of baseball pitchers. Given that bone hypertrophies in response to stress (Wolff's law), a finding of large disparities between humeral thickness in throwing and nonthrowing arms might indicate a need for training exercises to strengthen arm muscle and reduce the likelihood of injuries, said Dr. Patricia Cunningham.

The Duke study evaluated the feet of 14 basketball players from Duke and 12 players from North Carolina Central University prior to the start of the 2003 NCAA season. Three players were found to have bone marrow edema. One underwent ultrasound bone stimulation and played with a specially designed orthotic, finishing the season with no problems. A second player had a self-designed orthotic removed and also played without problems. The third player took no preventive measures and developed a stress fracture, missing most of the season.

The images were acquired on a 1.5T scanner and consisted of a long-axis fat-suppressed T2-weighted series.

All of the players were asymptomatic prior to imaging, so there was no real way to tell which ones might have bone marrow edema. The consequences to the team of even one player developing a stress fracture are severe enough, however, that screening MR is easy to justify, Major said.

The New York University study covered 11 varsity pitchers with an average age of 16.3 years. Bone hypertrophy is common in the femur in runners and in the tibia in ballet dancers. Typically, bone strengthens at the same pace as muscle, and when there is a mismatch, the likelihood of injury increases.

Cortical thickness ranged from 3 to 6 mm (mean of 3.5 mm) in the pitching arm and from 2 to 5 mm in the nonthrowing arm. In only one subject was the cortex thicker in the nonthrowing humerus.

When signs of cortical thickness indicate hypertrophy, it may be advisable to initiate training exercises to assure more equal levels of bone and muscle strength, Cunningham said.